Prolonged fasting induces long-lasting metabolic consequences in mice.
Level 5 - mechanism / opinion, no new human data
Preclinical animal experiment without human data
PubMed 32738733 · doi:10.1016/j.jnutbio.2020.108457
What was done
Adult male C57BL/6 mice were subjected to 48-hour fasting followed by refeeding (evaluated at 7 and 30 days), repeated fasting/refeeding cycles, or subsequent acute and chronic high-fat diet challenges. Outcomes measured included body weight, adiposity, lean body mass, energy expenditure, respiratory exchange ratio, locomotor activity, hypothalamic gene expression (Pomc, histone deacetylases, DNA methyltransferases), and histone acetylation in the ventromedial nucleus of the hypothalamus.
What was found
The abstract reports no exact numerical values or effect estimates. Following a 48-hour fast, 7 days of refeeding led to adiposity higher than baseline, incomplete recovery of lean mass and energy expenditure, persistent suppression of hypothalamic Pomc mRNA, and sustained reduction of histone acetylation in the ventromedial hypothalamus. At 30 days post-fast, mice retained higher body weight and fat mass than controls. Animals with cumulative fasting episodes showed lower energy expenditure and gained more body weight and fat mass when chronically fed a high-fat diet.
Why it matters
This study demonstrates that severe, prolonged fasting in mice can induce persistent metabolic and hypothalamic epigenetic changes that promote fat accumulation during subsequent refeeding.
Limits
The study was conducted entirely in mice without human subjects, and sample size is not stated in the abstract. A 48-hour fast is a severe metabolic challenge for mice that cannot be directly translated to human fasting regimens. No exact quantitative data, confidence intervals, or p-values are reported in the abstract.
Cited by
- supports Two days of fasting causes about a 20% loss of body weight in mice, whereas four days of fasting in humans causes only a 1% to 2% weight loss.